The most commonly utilized tank mixing systems utilize a shaft that extends below the liquid level of the tank and has an impeller attached thereto. The shaft and impeller combination is rotated to generate flow within the tank. In the case of cylindrical mixing tanks, baffles are often times necessary along the side wall of the tank in order to generate a desired top to bottom flow. While such mixing systems are generally accepted, they can create problems in certain mixing environments.
For example, in “clean” type mixing environments such as those commonly used in the pharmaceutical industry, it is required that the contents of the mixing tank be fully enclosed and sealed from the environment. Achieving this result with a rotating shaft and impeller arrangement can prove extremely difficult. Attempts have been made to utilize magnetic driving systems in order to eliminate the need for rotating seals, but these systems are expensive and difficult to maintain and clean. Further, the baffles often required by rotational type impellers make tank cleaning more difficult and expensive.
Accordingly, it would be desirable to provide a mixing arrangement, which is more readily suited for use in both open, and closed-tank mixing systems.